----------------------LED---------------------- Bit size = 7 micro inches = 0.18 micro meters "common cathode" 7-seg displays. ------ ----- +5V 5| |2,3,6,7,10 - Gnd 8| |13 -270ohm-|>-| sw 14|7490|1,12 ------------ 7|7448|12 -270ohm-|>-| | |9 --------------- 1| |11 -270ohm-|>-| | |8 --------------- 2| |10 -270ohm-|>-| | |11 -----*-------- 6| |9 --270ohm-|>-| ---- +5V 16| |15 -270ohm-|>-| | |14 -270ohm-|>-| ---- Gnd + **[Just a note from me, need a DE-BOUNCED switch circuit or the counter be counting the bounces of switch!! "switch point" sw is connected to +5V the counter will count by one. If you want to add a second digit, take a wire off the point marked * and connect this into sw point of an identical circuit. Those on the right are the bits of the LED display, by the way. You need to connect the "8" with its pins as follows: 13 ------ 15 | | 12 14 ------ 9 | | 11 ------ 10 can use 74LS90/74LS48 or even 74HC90/74HC48s, ---------------------------------------------------------------------------- Red LEDs 11-22+ lumens/watt by Agilent, Red-Orange LEDs - 21-22 maybe now 28.5 lumens/watt by Yellow-Green LEDs - 3-4 lumens/watt Green LEDs - 25-32+ sometimes 42 lumens/watt by Nichia, Blue LEDs - 7.5-probably 8, rarely 10 lumens/watt by Voltage drop at 20 mA was mostly 3.45-3.5 volts. Estimated luminous efficacy of emitted light was mainly 450-475 lumens per watt, maybe as low as 420-440 for bluest one and as high as 520-525 for one that was noticeably more of a lime green than the other 55 of the 56 good pieces. ---------------------------------------------------------------------------- lumen unit of light output, equal to 1 / (60 * pi) light emitted by one square centimeter ideal blackbody surface at melting point of platinum. IF spectrum differs from blackbody at melting point of platinum, equate lumens by applying official photopic function to the quantity of light at every wavelength present. ---------------------------------------------------------------------------- LED deposit three semiconductor layers on a substrate. Between an active region Between p-type and n-type semiconductor layers emits light when an electron and hole recombine. when forward biased holes from p-type and electrons from n-type driven into active region. light is produced by a solid state process called electroluminescence. layers of the LED emit light all the way around layered structure, and LED structure is placed in a tiny reflective cup so light from active layer reflected desired #####____ # / # /| # /____/ | # | | | # | | | # | | | # | | | __#__|____|_|_ / # /| / # / | / +1.9V / /|=> Light Out / / / | /_______________/ / /| |P_TYPE |/ / | |_______________| / /|__ |ACTIVE_REGION |/ / / /| |_______________| / / / | |N-TYPE |/ / / / |_______________| / / / |SUBSTRATE |/ / / _|_______________|_/ / | GND |/ |_______ ________| | | | | | | Wavelength of LED or Laser based on band-gap voltage voltage drop is close to the band gap of a forward biased diode. l = 1240 / E l = wave length in nm E = band-gap voltage red LEDs with a 1.9V drop run about 652 nm. (GaAs0.6P0.4) Calc_WaveLength =====Cut_Paste_Into_Formula_Calculator=================== LED_WaveLength_nm=1240/E_bandgap_V E_bandgap_V=1.9=BandGapVoltage_LED ---------------------------------------------------------------------------- Blue LED Lamps! in urban areas at night, blue lights have a tendency to stand out. for police emergency phones of blue lights was a result of "blue impact" or stimulation of blue-sensing light sensors in human eyes. Back when lumen was defined in terms of photopic function (1931 CIE "Y-bar" function), blumens equals lumens times ratio z to y chromaticity coordinates 1988 redefinition of photopic function messes this up, LED blue lights for police emergency phones. Most have usual 470 nm blue LEDs. current bright blue LEDs around 466-470 nm. blue peak of human vision is a little below 450 nm.